RV/Van Life Solar Panel Sizing Calculator
Created by: Ethan Brooks
Last updated:
Size your RV or van life solar panel system based on your daily energy consumption, peak sun hours for your location, and system efficiency factors. Get recommendations for panel configurations and placement.
What is an RV/Van Life Solar Panel Sizing Calculator?
An RV/Van Life Solar Panel Sizing Calculator helps you determine exactly how many watts of solar panels you need for your camper van, motorhome, or RV. By entering your daily electrical consumption and local sun conditions, you can calculate the right solar array size to keep your batteries charged while living off-grid.
Whether you're converting a Sprinter van, outfitting a travel trailer, or building a skoolie, properly sizing your solar system is crucial for reliable off-grid power. This calculator accounts for real-world factors like panel efficiency, temperature losses, and system overhead to give you accurate recommendations.
Understanding RV Solar Sizing
Daily Consumption (Wh): Total energy used per day by all appliances and devices
Peak Sun Hours: Hours of full-intensity sunlight (1000W/m²) your location receives
System Efficiency: Typical 70-85% due to heat, wiring losses, and charge controller overhead
Buffer Factor: 20-30% extra capacity for cloudy days and seasonal variation
Basic Formula: Panel Watts = (Daily Wh ÷ Peak Sun Hours ÷ Efficiency) × Buffer
Frequently Asked Questions
How many watts of solar panels do I need for my van?
Most van builds need 200-600 watts of solar. Calculate your daily Wh consumption, divide by average sun hours (typically 4-6), add a 30% buffer for inefficiency, and you'll have your panel wattage. A basic setup with lights, fridge, and devices needs around 200W; full-time living with more appliances needs 400-600W.
What's the difference between peak sun hours and daylight hours?
Peak sun hours (PSH) measure solar intensity equivalent to 1000W/m², not total daylight. A location with 12 hours of daylight might only have 4-5 peak sun hours. Use PSH for calculations as it accounts for morning/evening low-angle sun and cloud cover.
Can I run my RV air conditioner on solar?
Running AC on solar alone is challenging. A typical RV AC uses 1200-1500W continuously. You'd need 800W+ of panels and a large battery bank (400Ah+ lithium). Most people use shore power or a generator for AC and solar for everything else.
Should I get rigid or flexible solar panels for my van?
Rigid panels are more efficient (18-22% vs 15-18%), durable, and cheaper per watt. Flexible panels are lighter and conform to curved roofs. For most van builds, rigid panels mounted with a small air gap perform better and last longer.
How much solar do I need to charge my battery bank?
Your solar should be able to replace daily consumption plus 20-30% extra. If you use 100Ah daily from a 12V system (1200Wh), you need panels that produce at least 1500Wh. With 5 peak sun hours, that's 300W of panels minimum.
Do I need an MPPT or PWM charge controller?
MPPT controllers are 15-30% more efficient than PWM, especially in cold weather or with panels wired in series. For systems over 200W, MPPT is worth the extra cost. PWM works fine for small, simple setups under 200W.
How do clouds and shade affect solar panel output?
Clouds reduce output by 25-90% depending on thickness. Partial shade is worse than full clouds because it creates hot spots. One shaded cell can reduce an entire panel's output by 30-50%. Use panels with bypass diodes to minimize shade impact.
What's a realistic expectation for solar panel output?
Expect 70-80% of rated wattage in real-world conditions. A 100W panel typically produces 70-80W peak and generates 300-400Wh daily with 4-5 peak sun hours. Always size your system for worst-case scenarios, not ideal conditions.
Sources and References
- NREL, "Solar Resource Data and Tools", National Renewable Energy Laboratory, 2024
- Victron Energy, "Off-Grid Solar System Sizing Guide", victronenergy.com
- Will Prowse, "Mobile Solar Power Made Easy", 2023 Edition